Kajian Pemanfaatan Energi Arus Laut di Indonesia

Masih belum banyak lembaga penelitian yang melakukan kegiatan penelitian tentang potensi energi arus laut di Indonesia. Tetapi mengingat cadangan sumber energi fosil yang semakin lama akan terus berkurang, maka penelitian tentang potensi energi ini harus terus dilakukan .Untuk tujuan tersebut, Pemerintah telah mengeluarkan sejumlah kebijakan agar penelitian mulai lebih fokus pada pengembangan energi terbarukan khususnya dari laut, mengingat Indonesia sebagai Negara Kepulauan yang memiliki banyak Selat.Pemerintah telah berkomitmen untuk dapat meningkatkan kontribusi Energi Baru Nasional dari 17% saat ini menjadi 23 % pada tahun 2025 nanti. Turut berkontribusi dalam semangat tersebut,Balai Teknologi Hidrodinamika (BTH) telah meng-inisiasi kegiatan penelitian sumber energi arus laut melalui penelitian berbagai tipe turbin Poros vertikal sejak tahun 2006. Terakhir pada tahun 2017 telah dilakukan uji kinerja Turbin Ganda (twin turbine) di Jembatan Suramadu.Meskipun belum mencapai hasil maksimal, tetapi hasilpenelitian tersebut diharapkan dapat meng-inisiasi dan dijadikan sebagai referensi bagi kegiatan penelitian Turbin arus laut lainnya. Penelitian juga telah menghasilkan dua buah sertifikat Paten. Paper ini hanyalah sebagai informasi perkembangan penelitian energi arus laut di BTH dan prospek ke depannya bagi pengembangan penelitian di Indonesi

Micrometer-Thin Crystalline-Silicon Solar Cells Integrating Numerically Optimized 2-D Photonic Crystals

A 2-D photonic crystal was integrated experimentally into a thin-film crystalline-silicon solar cell of 1-{\mu}m thickness, after numerical optimization maximizing light absorption in the active material. The photonic crystal boosted the short-circuit current of the cell, but it also damaged its open-circuit voltage and fill factor, which led to an overall decrease in performances. Comparisons between modeled and actual optical behaviors of the cell, and between ideal and actual morphologies, show the global robustness of the nanostructure to experimental deviations, but its particular sensitivity to the conformality of the top coatings and the spread in pattern dimensions, which should not be neglected in the optical model. As for the electrical behavior, the measured internal quantum efficiency shows the strong parasitic absorptions from the transparent conductive oxide and from the back-reflector, as well as the negative impact of the nanopattern on surface passivation. Our exemplifying case, thus, illustrates and experimentally confirms two recommendations for future integration of surface nanostructures for light trapping purposes: 1) the necessity to optimize absorption not for the total stack but for the single active material, and 2) the necessity to avoid damage to the active material by pattern etching.Comment: Authors' postprint version - Editor's pdf published online on Nov.

Absorbing photonic crystals for thin film photovoltaics

The absorption of thin hydrogenated amorphous silicon layers can be efficiently enhanced through a controlled periodic patterning. Light is trapped through coupling with photonic Bloch modes of the periodic structures, which act as an absorbing planar photonic crystal. We theoretically demonstrate this absorption enhancement through one or two dimensional patterning, and show the experimental feasibility through large area holographic patterning. Numerical simulations show over 50% absorption enhancement over the part of the solar spectrum comprised between 380 and 750nm. It is experimentally confirmed by optical measurements performed on planar photonic crystals fabricated by laser holography and reactive ion etching.Comment: 6 pages. SPIE Photonics Europe pape

Gas rate measurements in a two-phase flow by acoustic means

Authors present an ultrasonic method for measuring the role of dissolved gas in a liquid. The aim of this analyse is to control the gas rate in a low temperature and high pressure flow of liquid hydrogen or liquid oxygen. The interest is to prevent the defective behaviour of carburant loading pumps in rocket engine. A preliminary study is realised on a water column, without average flow, to the basis of which are generated bubbles of air. The ultrasonic method used to detect the gaseous phase appearance consists in recording the amplitude of waves transmitted through the two-phase flow. A technical is proposed to measure average and local gas rate. Acoustic tests have been realised on two types of columns (glass tube with square section and polymetacrylate tube of round section). In each configuration and for several measuring frequencies (134 to 600 kHz), results show a quasi-linear decreasing of the amplitude (in logarithmic coordinate) as the air gas rate increases (0 to 9%)

Letter to the Editor: Prognosis of idiopathic intracranial hypertension in Saudi Arabia

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